1. Field of the Invention
This invention relates to computer systems and, more particularly, to computer systems including circuitry for decomposing graphic figures to be displayed or manipulated into portions which may be stored in a display buffer.
2. History of the Prior Art
A major problem in utilizing computers to provide graphic displays is that for a single frame of graphical material to be presented on a cathode ray tube (CRT), it is necessary to store an indication of the information which is to be displayed for each position (pixel) which is to appear at that position on the cathode ray tube. With large and detailed displays, the number of pixels on the cathode ray tube may be approximately one thousand or greater in a horizontal direction and a like number in the vertical direction giving a total of approximately one million or more pixels about which information is to be stored. In a preferred system which is capable of providing a number of different colors on the cathode ray tube, each of these pixels contains eight bits of digital information specifying the particular color output. Consequently, approximately eight million bits of information needs to be stored for each frame to be presented at the output.
Not only does color information have to be provided for each pixel for each frame of the display, but in generating graphic displays, the usual method of determining the shapes of figures requires that various algorithms be applied to the geometric vertices of those figures. If this is handled by the software of the system, computing the positions of each point to be displayed and determining the data to be displayed at that point slows the operation of the system to a point where operations such as animation are essentially impossible. For this reason, various systems utilizing hardware to speed the operation have been suggested. One method for speeding the operation is to use two output frame buffers, and load one buffer while the other is being scanned to the display. Such a system significantly speeds the operation but requires essentially twice as much memory to accomplish the storage.
It is, therefore, an object of the present invention to speed the operation of computer systems.
It is another object of the present invention to provide circuitry for decomposing a graphic object into portions which may be rapidly processed and scanned into a display buffer so that graphic figures may be generated by the use of quadrilateral subportions.
It is an additional object of the present invention to provide circuitry for processing and scanning graphic information into a display register rapidly enough that a single buffer may be utilized for the display of animated programs.